| dc.description.abstract | Due to the extremely high toxicity, removal of dioxin from gas streams has been one of the most popular research topics in recent years. The most commonly used removal technologies include adsorption by activated carbon and catalytic decomposition. The latter is better because it can decompose dioxin, rather than phase transfer. The catalytic decomposition of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofruans (PCDFs) was investigated over commercial V2O5-WO3/TiO2-based catalysts at controlled temperature, water vapor content and space velocity in this study.
According to experimental results, at space velocity of 5000 hr-1 and dioxin concentration of 4.1 ng-TEQ/Nm3, the conversion of PCDD/Fs over V-T catalysts increases as operating temperature is increased. The catalytic conversions of PCDD/Fs increased from 57% to 77%, as the temperature is inceased from 220℃ to 280℃. At space velocity of 10000 hr-1, the difference of conversion is only 10% from 220℃ to 280℃. The experimental results indicate that higher space velocity results in lower conversions of PCDD/Fs, and in this situation it has smaller effect with operating temperature. At fixed temperature and PCDD/Fs concentration, catalytic decomposition of dioxins increases with decreasing space velocity due to longer retention time. Of the seventeen 2,3,7,8-substituted PCDD/Fs congeners, the conversion of dioxin increases with decreasing chlorination degree because higher chlornation congeners have higher boiling point and stable structure.
Finally, this study combined integral reaction and Mars-Van Krevelen model to calculate the activation energies of OCDD and OCDF, respectively. The activation energies of OCDD and OCDF are calculated as 24.8 KJ/mole and 25.2 KJ/mole, respectively. | en_US |